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(Stroke. 2004;35:506.)
© 2004 American Heart Association, Inc.

Original Contributions

Editorial Comment—Can MRI Reliably Detect Hyperacute Intracerebral Hemorrhage? Ask the Medical Student

Neuro Endovascular Surgery Interventional NeuroRadiology, University of Miami Jackson Memorial Hospital, Miami, Florida

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Although never formally tested, a CT is required to exclude intracerebral hemorrhage (ICH) in acute stroke prior to thrombolysis. Therefore, centers that use MRI in acute stroke must in addition obtain a CT to safely rule out ICH.

Despite traditional skepticism, MRI is intrinsically able to detect hyperacute ICH. Such capability is based on the magnetic susceptibility effect of deoxyhemoglobin. In ICH, hemoglobin extravasates in an environment with a low O₂ concentration, low pH, and high CO₂. Because of the Bohr effect, such changes promote the formation of deoxyhemoglobin extending from the periphery of the hematoma toward the center. Deoxyhemoglobin has 4 unpaired electrons and is therefore paramagnetic ( >0). As such, it produces magnetic inhomogeneities that result in local T2* relaxation enhancement. Obviously, the MR contrast of deoxyhemoglobin is highly dependent on the mode of imaging acquisition. For instance, deoxyhemoglobin induced signal loss (darkening) is most pronounced in sequences that are T2* weighted such as conventional gradient echo (GE) and both spin-echo and gradient-echo echo-planar sequences.¹

Atlas and Thulborn reported signal loss on long TR/TE, and GE images in a rat model of ICH.² Distinctive signal loss was present at the earliest imaging time point (1 hour after the induction of the hematoma). Several authors reported clearly detectable changes on T2*-weighted imaging in patients with ICH imaged between 23 minutes and 6 hours after symptom onset.^3,4 In 5 patients with ICH imaged within 2 hours after symptom onset, distinctive patterns of hyperacute ICH and absence of signs of . . . [Full Text of this Article]